The present invention relates generally to the application of automatic meter reading (AMR) or advanced metering infrastructure (AMI) modules on a gas meter and more particularly to a meter reading system capable of monitoring gas usage on a sealed mechanical gas meter.
Mechanical measurement devices are widely installed in a variety of applications to provide control and measurement functionality. These measurement devices, such as a gas meter or a pressure gauge for example, provide a visual indication of usage or operating performance. These measurement devices are popular due to the high reliability and long operational life spans. As a result a large population of such devices are installed in the field.
One type of such device is the utility gas meter 20 as is illustrated in FIG. 1 and FIG. 2. The meter 20, sometimes referred to as a “tin case meter”, includes a housing 22 that is sealed to prevent tampering and leakage. The housing 22 includes an inlet 32 and an outlet 34 that allow gas to enter and exit the meter 20. The inlet 32 and outlet 34 are coupled to a measurement mechanism (not shown) that meters the amount of gas passing through the meter 20. Gas meters use a number of different types of measurement mechanisms such as but not limited to bellows, diaphragm, rotary, turbine, orifice, ultrasonic flow, or coriolis mechanisms.
A window 24 is provided on the meter to allow utility personnel and customers to view of a set of dials 26. The set of dials 26 includes a first set of cumulative dials 28 that the utility personnel use for recording the amount of gas consumed. The set of dials 26 also includes a measurement dial 30 that is coupled to the gas meters measurement mechanism (not shown). The measurement dial 30 rotates in response to movement of the measurement mechanism. The measurement dial 30 is further coupled to rotate the cumulative dials 28 as gas passes through the meter 20. On a periodic basis, utility personnel make a visual inspection of the meter 20. During this inspection, the utility personnel note the amounts indicated on the cumulative dials so that the consumer can be charged for the appropriate usage.
To improve efficiencies in operations, businesses often desire to remotely read meters to avoid the costs associated with manually reading the measurement devices. Some meters may be located in inconvenient locations, such as a residential basement or kitchen for example. If personnel cannot access the meter, such as when no one is home where the device is located, the personnel are forced make repeated trips or estimate the measurement readings. As a result, many modern gas meters may include communications capability added into the device that allows the automated reading of the meter from a remote location.
Due to the large installed base of utility gas meters, it is cost prohibitive to replace all installed meters. For example, production of the tin case type gas meter was initiated in the 1920s and continued until the 1970s with millions of units produced and still in use. The operational longevity of these mechanical meters greatly extends the amount of time it would take to convert the entire installed base to a more modern meter. To alleviate these issues, automated reading devices have been proposed to retrofit to the meter and allow remote monitoring of the meter. However, these remote monitoring devices have been limited to use with meters where the measuring mechanisms can be removed on-site without allowing gas to escape into the atmosphere.
Most tin case utility gas meters are sealed and the meter was designed to contain no serviceable parts. As a result, the attempts to retro-fit existing utility gas meters with automated meter reading equipment have met with little success for the sealed tin cased meter since the measuring apparatus can not be removed with breaching the sealed enclosure. Further complicating these attempts at adapting these remote reading modules to tin cased meters is that the cases are typically made of a ferrous metal which blocks attempts to use some noninvasive measurement means, such as magnetic devices.
Another issue encountered with the proposed automated reading devices is that they must comply with the stringent requirements of public utility boards and agencies. These agencies place a number of requirements on measurement devices to ensure that the consumer is being accurately charged for the gas consumed. Another regulation requires that the consumer and utility personnel still be able to view the dials 26 after the automated reading device is installed. This ensures that the consumers can check the usage themselves and also allows utility personnel to check for leaks when the gas system is serviced.
Thus, while existing gas meter reading devices are suitable for their intended purposes, there remains a need for improvements in sealed metering devices, such as sealed tin cased meters. In particular, there remains a need for improvements in providing a gas meter reading system that allows for automated reading of all type of gas meters, regardless of construction, while complying with governmental and industry requirements.